Mounting for diaphragms for acoustical instruments



Feb. 27, 1923.

A. C. LESCARBOURA ET AL.

MOUNTING FOR DIAPHRAGMS FOR ACOUSTICAL INSTRUMENTS.

FILED NOV. 5,1918.

INVENTOR fll/Sfifl 6f Amcarboum Alumna Pr Band A TTOR/VEYS pitched tones.

Patented Feb. 27, 1923.

UNITED STATES? PLAINFIELD, NEW JERSEY, ASSIGNOBS TO THE AEOLIAN COMPANY, A CORPORA- TION OF CONNECTICUT.

MOUNTING FOB DIAPHRAGMS FOB ACOUSTICAL INSTRUMENTS.

Application filed November 5, 1918. Serial No. 261,281.

To all whom it may concern:

Be it known that we, AUSTIN C. LESCAR- BOURA, of the city of New York, in the county of New York and State of New York, and ALEXANDER RUSSELL Bonn, ofthe city of Plainfiel-d, in the county of Union and State of New Jersey, both citizens of the United States, have invented a new and useful Improvement in Mountings for Diaphragms for Acoustical Instruments, of which the following is a full, clear, and exact description. i

Our invention relates particularly to diaphragms of phonographs, although it is also applicable to other types of acoustical instruments in which diaphragms are used.

It is well known in the art of phonography that a diaphragm of small area or one whose natural period of vibration is high, Wlll re- "produce satisfactorily tones 'in the upper and records it is more important to reproduce clearly and fully the high-pitched tones, while in othersthe reverse holds true. It is our purpose to provide a diaphragm which can be adapted to reproduce clearly and fully either high-pitched tones or lowpitched tones.

Accordingly our invention provides a single diaphragm whose natural peroid of vi bration can be varied at the will of the operator in order to adapt it to the reproduction of high-pitched ,tones or of low- Said variation of the period of vibration is effected by varying the active area of said diaphragm, and by active area we mean. that part of the diaphragm that is wibrated or actuated by the reproducing stylus. Our invention also'provides for variation of tension of said diaphragm in cases in which the material of which'said diaphragm is composed has sufficient elasticit 'to permit of having sion varied. hen the tension is increased the arrangement is such that the active area its ten-' of the diaphragm is simultaneously reduced, and vice versa, so that the variation in the diaphragms natural period of vibration produced by variations of tension of said diaphragm compliment the variation in said diaphragms natural period of vibration produced by varying the active area of said diaphrag PATENT OFFICE.

' AUSTIN C. LESCARBOUKA, OF NEW YORK, N. Y., AN'D ALEXANDER RUSSELL IBOND, OF

With this and other objects in.view our v invention consists of novel features and parts and combinations of the same, as will be more fully described hereinafter and then pointed out in our claims.

Reference is to be had to the accompanying drawing forming part of this specification, in which similar characters of reference indicate corresponding parts in all the figures.

Figure 1 is a front elevation of a phonograph sound box embodying our invention.

Figure 2 is a sectional view taken on the line 11, Figure 1, viewed in the direction .of the arrows.

Figure 3 is a viewsimilar to Figure 2 in a which, however, a diaphragm is shown with its active area reduced.

Figure 4 is a front elevation of a modification of .our invention. I I

Figures 5 and 6 are sectionalwiews taken on the line 4-4 of Figure 4, viewed in the direction of the arrows and showing the diaphragm with its active area large and small, respectively, and Figure 7 is a side elevation of the sound box shown in F igure 4.

Referring to Figures 1, 2 and 3, A represents a casing of a sound box in whicha diaphragm B is secured by means of a retaining ring C, said ring bein place by means of screws D. T e manner of securing said diaphragm may be varied at will to conform with the best practice of the art and we wish it to be understood that we do not confine our'invention to the specific method of securing the diaphragm which is shown in the accompanying drawings. Connected to the diaphragm B is a stylus bar E fulcrumed at F to the casin A and furnished with a stylus G adapte to bear on a phonograph record. The

held in I bar-could be altered so as to adapted our with the mechanism we are about to describe for varying the active area of the diaphragm. I

'The casing A may be secured in any wellknown manner to a tone arm H.

Within the casing A there is an annular flange I formed with a lip J. Said lip is virtuallyan annular fret against which the diaphragm Bmay be pressed by a ring K threaded into the retaining 'ring C, said ring K being formed with a lip L registering with the' lip J. The ring K is formed with lugs or finger pieces M to facilitate turning said ring. 3

When the parts are in the position indicated in Figures 1 and 2 the active area of the diaphragm B is limited by the retaining ring C, but on turning the ring K clockwise the lip L impinges upon the diaphragm and bears it down upon the lip J Between the lips L and J the diaphragm is firmly gripped and thus the active area of the diaphragm is stopped off andbounded by lips L and J.

When the partscare in the ,position indicated in Figure 2 there should be sufficient clearance between the lips J and L and the diaphragm B to preventsaid diaphragm from touching said lips when vibratedby the stylus G. Ring Kmay be threadedinto' ring D with a thread of such pitch that when saio ring K is turned through a partial rotation sufficient to bring the finger pieces M from the position shown in full lines to that shown by dotted lines in Figure 1, the diaphragm B will have been flexed to the position inclicated in Figure 3. At the same time the diaphragm B-wi'll be subjected totension by the fiexure produced by the pressure of ring K, thus further inc easing the natural period of vibration of said diaphragm.

As diaphragms composed of certain materials are not adapted to be flexed to the extent required by the' construction shown in Figures 1 2 and 3, we have provided a modification shown in Figures 4: to 7 inclusive, in which the active area-of a diaphragm can be varied without flexing said diaphragm. e

In said modified construction A represents a' casing in-which a diaphragm B is secured by means of a'reta-ining ring C held in place by means of screws D. At E is a stylus bar fulcrumed at F in the usual manner and furnished with a stylus G adapted to bear on a phonograph record. The cas; in A is mounted on a tone arm H. Threaded into the casing A at the inner side of the diaphragm is-an annular member I formed on its inner periphery with a lip J adapted to be moved into engagement with the diaphragm B. On the opposite side of position.

said diaphragm there is another similar annular member K formed with a lip L and adapted to be moved into engagement with the diaphragm B with said lip L in registry with said lip J but on the opposite side of the diaphragm B. Secured to member K is a handle N projecting through a,

in full lines in Figures a and 7 to a point B atwhich said handles are indicated by dotted lines in Figure 4 the members K and I will be moved one toward the other until they grip the diaphragm between them,tas shown in Figure 6. In the latter position the ace tive area of the diaphragm is reduced with out, however, imposing anytension upon said diaphragm.

It will be observed that slots P and Q, extend beyond the point R at which the diaphragm isgripped when the two handles N and O are simultaneously moved to clamping The purpose of the extension of said slots is to permit of placing said diaphragm under some tension if such tension be found desirable. If the handle N be moved down beyond the point R as indicated by dotted lines in Figure 7 the diaphragm B will be flexed, and the degree of flexur is.

"the handle 0 may be moved down until. the

lip J". clamps said memberK. r

Having thus described our invention, what we claimas new and desire to secure by Letters Patent is 1. A mounting of thecharac ter described comprising a vibratory diaphragm, -means diaphragm against the for supporting the same providing a norinal vibrant pitch therefor, and means for varying the vibrant pitch thereof comprising a pair of diaphragm engaging members of substantially equal diameter relatively movable into engagement with the opposite sides of the diaphragm to clamp the latter and to apply tension thereto.

2. A mounting of the character described comprising a vibratory diaphragm, means for securlngthe periphery thereof and pro-- 'viding a normal vibrant pitch therefor, and

opposed diaphragm engaging members nor- -mally disengaged f om the diaphragm but relatively movable ln-to engagement with its opposite sides to clamp and displace the intermediate portion of the diaphragm late'rally, thus subjecting the diaphragm tovariant tension.

phragm to tension.

5. In a mounting of the character described comprising a vibratory diaphragm having means for supporting its periphery in a normal plane, aplurality of opposed clamping" members adapted to clamp the diaphragm between them and to Hex the intermediate portion of the diaphragm out of said nor mal plane.

6. The combination of a sound box. a diaphragm having means for supporting its periphery in a normal plane. and opposed clamping members at opposite sides 01 the diaphragm and normally disengaged therefrom, said clamping members being rela tively movable to clamp the diaphragm between them and to subject the diaphragm to a variant tension.

7. In a mounting as characterized comprising a vibratory diaphragm, a. plurality of opposed clamping members adapted to vary the normal vibrant area. of said diaphragm while maintaining said diaphragm in the normal plane thereof, said clamping members being operable atwill to flex said diaphragm outof said normal plane.

8. A diaphragm mounting comprising means for clamping themarginal area of the diaphragm and a pair of coacting clamping members of like contour, normally spaced from opposite faces of the diaphragm but relatively movable into clamping engagement therewith to decrease the normal vibratory area of the diaphragm, said clamping members being also operable to flex the diaphragm out of its normal plane.

9. The combination with a sound box and a diaphragm mounted therein, of gasket members of substantially the same diameter adjustably supported at opposite sides oi the diaphragm and means for shifting both said membeis either toward or away from the diaphragm, to clamp the diaphragm between them and disengage them from the diaphragm respectively and for flexing the diaphragm out of its normal plane.

10. A sound box comprising base and cover members having reversely screwthreaded seats, reversely threaded diaphragm-engaging members engaged with said seats and adiaphragm mounted in the sound box between said members.

11. The combination with a sound box and a diaphragm mounted therein, of diaphragm-area reducing members mounted at opposite sides of the diaphragm and means for shifting both said members either toward or away from the diapl1r-agm,'said members being capable of clamping the diaphragm to reduce its vibrant area without subjecting the diaphragm to tension and also capable of subjecting the diaphragm to tension. 1

In testimony whereof we have signed our names to this specification in the presence of two subscribing witnesses.

AUSTIN C. LESCAR-BOURA. ALEXANDER RUSSELL BOND.

Witnesses:

PHILIP D. RoLLHoUs, GEORGE H. EMSLIE. 

